"Yolanda" <Yoly1962@aol.com> wrote in messagenews:v6lav0pqi86p5cfimb1sfdv1j60b8b6v71@4ax.com...

> Darrell:>> I was quite impressed by your response. I have a question what is the> formula to arrive at every possible 4 digit combination using series> 0-9 for instance last 4 telephone digits.>> Please respond to my personal email Yoly1962@aol.com I appreciate> this.

This was asked and answered just last week. Just use the fundamental counting principle.